Add a maxSize option to limit user-specified sizes (#803)

* Fix color support for stretchy, strikethrough, and fbox
Summary:
Stuff like `\red{\overbrace{AB}}` works now in addition to `\color{red}{\overbrace{AB}}`. Strikethrough now respects color. The Firefox in the screenshotter doesn't seem to support `background-image` + `mask`, but I manually tested that the latest Firefox does.

Test plan:
Ran `make`, then tested in latest Chrome and Firefox to ensure color support was working, then ran `make screenshots`.

* Add a maxSize option to limit user-specified sizes (#109)

* Simplify maxSize logic and add unit test
* Clamp negative maxSize to zero
* Use a default maxSize of infinity to remove branching in calculateSize

src/Options.js

@@ -51,6 +51,7 @@ class Options {
         this.phantom = data.phantom;
         this.font = data.font;
         this.sizeMultiplier = sizeMultipliers[this.size - 1];
+        this.maxSize = data.maxSize;
         this._fontMetrics = null;
     }
 
@@ -66,6 +67,7 @@ class Options {
             color: this.color,
             phantom: this.phantom,
             font: this.font,
+            maxSize: this.maxSize,
         };
 
         for (const key in extension) {

src/Settings.js

@@ -24,6 +24,7 @@ class Settings {
         this.errorColor = utils.deflt(options.errorColor, "#cc0000");
         this.macros = options.macros || {};
         this.colorIsTextColor = utils.deflt(options.colorIsTextColor, false);
+        this.maxSize = Math.max(0, utils.deflt(options.maxSize, Infinity));
     }
 }
 

src/buildTree.js

@@ -16,6 +16,7 @@ const buildTree = function(tree, expression, settings) {
     // Setup the default options
     const options = new Options({
         style: startStyle,
+        maxSize: settings.maxSize,
     });
 
     // `buildHTML` sometimes messes with the parse tree (like turning bins ->

src/units.js

@@ -90,7 +90,7 @@ const calculateSize = function(sizeValue, options) {
             scale *= unitOptions.sizeMultiplier / options.sizeMultiplier;
         }
     }
-    return sizeValue.number * scale;
+    return Math.min(sizeValue.number * scale, options.maxSize);
 };
 
 module.exports = {